There are a number of ways to attach a sunvisor to a roof member in a vehicle. The conventional and widely used method employs the use of screws driven by assembly personnel within the vehicle frame with screw guns. This method of assembly is sometimes referred to as a "layer build." In general, each component of the car roof interior is positioned adjacent each other as the vehicle frame travels down an assembly line. First, an attachment fastener is installed in the vehicle frame, whereupon a headliner is positioned adjacent the frame. Next, the visor mounting bracket is attached by inserting screws or the like through the mounting bracket into the attachment fastener.
The problems associated with this type of operation are well known. This process requires that the operators assembling the sunvisors to the roof of the vehicle be able to position the screw guns at odd angles within the vehicle. Due to the odd assembly angles coupled with the fact that the operator must physically hold the visor in place while driving the screws, and go into and out of the vehicle multiple times, ultimate operator fatigue ensues and headliners may be readily subject to damage. Such is not only costly, but also raises the ergonomic issues with respect to the wear and tear on an operator's body which is an area of concern within the automotive industry.
Thus, a "modular build" process of assembly that minimizes or eliminates the operator from physically entering the vehicle to attach components to the vehicle structure, particularly one which minimizes or eliminates the assembly personnel from entering the vehicle with a screw gun once soft trim is attached, is far preferable from an ergonomic, a cost, and an efficiency of manufacturing perspective. In this method, the attachment fastener, headliner and visor mounting bracket are attached to one another in a specially designed fixture. This completed assembly is then inserter into the vehicle frame and secured thereto with minimal application of force. Unfortunately, this method currently requires up to 40 pounds of force to ensure installation and may require the use of rubber mallets to do so. Of course, these mallets may inadvertently damage the headliner.
Many attempts have been made in the past to employ a modular assembly for attaching the sunvisor system directly to the vehicle headliner or installing the system independently of the headliner to the vehicle roof. At least two known directions have been taken, one employing polymeric devices and the other employing the use of steel fasteners. With respect to these two directions, each has been employed with varying levels of success.
With respect to the polymeric device, it can either employ a modular assembly mounted directly to the vehicle headliner or one which is installed independently of the headliner to the vehicle roof. The modular assembly is constructed with the headliner compressed between a visor mounting bracket that is visible from within the vehicle and a polymeric attaching device that rests on the opposite non-visible side of the headliner. This securely holds the visor to the headliner through a compressive force. This system is then installed into the vehicle as one complete overhead assembly with respect to, but not limited to, the sunvisors. The sunvisor, which may be installed independently of the headliner to the vehicle roof in a non-modular assembly, is usually but not always the same type of polymeric material that is employed in the device to mount the visor to the vehicle roof. In order for this system to function, the polymeric material is required to be under a constant state of preload after installation in order to hold the visor securely to the sheet metal roof throughout the operating life of the vehicle. However, over a length of time, the polymeric device, while under a state of preload, tends to creep and the visor loosens noticeably with respect to the attachment to the sheet metal within the vehicle. Customer use of the visor accelerates this condition by subjecting the polymeric attaching device to cyclic loading, thus stressing the visor assembly and in particular the polymeric attaching device. Another concern is that a bur, created during the forming and blanking of the sheet metal attaching aperture in the roof or roof member support structure may be present. Such a bur may cut, scribe or etch a line in the polymeric attaching device. As a result, a fatigue line develops during cyclic loading of the visor causing the polymeric mounting device to fatigue, loosen, and/or fail prematurely, i.e., before the end of the expected life of the vehicle.
The second type of mounting system is a steel fastening device. This system is employed in the assembly much like the polymeric attaching device, and is subject to the same assembly processes as the polymeric device. The benefits of the steel type fastening system is its ability to withstand long term pre-load as well as the ability to withstand greater loads, especially those which are encountered during cyclic loading of the sunvisor with no noticeable loss of retention. The steel fastening system has the ability to accommodate a wider range of sheet metal variance as well as retain the structural integrity of the mounting system when subject to a bur condition in the roof member aperture. However, during assembly of the visors to the vehicles, this mounting system requires a great deal of force to install the system in the vehicle frame due to the configuration of the mounting system. Furthermore, this mounting system is unable to accommodate an allowable variance in sheet metal thickness coupled with an allowable bur condition with respect to assembly. Also, under these and similar conditions, it is often unclear whether or not all surfaces of the fastening device are properly engaged and mounted to a mounting surface in the vehicle roof aperture because the mounting system gives no audible feedback to assembly personnel. Other drawbacks of the device arise during visor use within the vehicle. A majority of the mounting systems in use locate the engagement surfaces of the visor mounting bracket in close proximity to the center line on the visor elbow rod, thus concentrating the forces that are applied to the mounting system across a small area proximate to the engagement surfaces of the mounting system. This allows movement of the mounting system and as a direct result, there is visible perceptible movement of the polymeric visor mounting bracket with respect to the mounting system as well as perceptible deflection of the headliner system proximate and adjacent to the polymeric sunvisor mounting bracket which is an undesirable condition.